Effects of Ionizing Radiation on Cardiac Implantable Electronic Devices (CIEDs) in Patients with Esophageal Cancer Undergoing Radiotherapy: A Pilot Study

(1) Background: The prevalence of cancer patients relying on cardiac implantable electronic device (CIED) is steadily rising. The aim of this study was to evaluate RT-related malfunctions of CIEDs. (2) Methods: We retrospectively analyze sixteen patients with esophageal cancer who were treated with radiotherapy between 2012 and 2022 at the University Hospital Heidelberg. All patients underwent systemic evaluation including pre-therapeutic cardiological examinations of the CIED functionality and after every single irradiation. (3) Results: Sixteen patients, predominantly male (14) with a mean age of 77 (range: 56-85) years were enrolled. All patients received 28 fractions of radiotherapy with a cumulative total dose 58.8 Gy. The mean maximum dose at the CIEDs was 1.8 Gy. Following radiotherapy and during the one-year post-radiation follow-up period, there were no registered events associated with the treatment in this evaluation. (4) Conclusion: The study did not observe any severe CIED malfunctions following each radiation fraction or after completion of RT. Strict selection of photon energy and alignment with manufacturer-recommended dose limits appear to be important. Our study showed no major differences in the measured values of the pacing threshold, sensing threshold and lead impedance after RT.

The Contribution of Secondary Particles Following Carbon Ion Radiotherapy to Soft Errors in CIEDs

Introduction: While carbon ion radiotherapy is highly effective in cancer treatment, it has a high risk of causing soft error, which leads to malfunctions in cardiac implantable electrical devices (CIEDs). To predict the risk of malfunction prior to treatment, it is necessary to measure the reaction cross-sections and contributions to the soft error of secondary particles generated during treatments. Methods: A field-programmable gate array was used instead of CIEDs to measure soft errors by varying the energy spectrum of secondary particles. Results and discussion: The reaction cross-sections measured for each secondary particle were 3.0 × 10-9, 2.0 × 10-9, 1.3 × 10-8, and 1.5 × 10-8 [cm2/Mb] for thermal neutrons, intermediate-energy neutrons, high-energy neutrons above 10 MeV, and protons, respectively. The contribution of high-energy neutrons was the largest among them. Our study indicates that to reduce the risk of soft errors, secure distance and appropriate irradiation directions are necessary.

Incidence and Predictors of Cardiac Implantable Electronic Devices Malfunction with Radiotherapy Treatment

Aims: To investigate the incidence of cardiac implantable electronic devices (CIED) malfunction with radiotherapy (RT) treatment and assess predictors of CIED malfunction. Methods: A 6-year retrospective analysis of patients who underwent RT with CIED identified through the radiation oncology electronic database. Clinical, RT (cumulative dose, dose per fraction, beam energy, beam energy dose, and anatomical area of RT) and CIED details (type, manufacturer, and device malfunction) were collected from electronic medical records. Results: We identified 441 patients with CIED who underwent RT. CIED encountered a permanent pacemaker (PPM) (78%), cardiac resynchronization therapy—pacing (CRT-P) (2%), an implantable cardioverter defibrillator (ICD) (10%), and a CRT-defibrillator (CRT-D) (10%). The mean cumulative dose of RT was 36 gray (Gy) (IQR 1.8–80 Gy) and the most common beam energy used was photon ≥10 megavolt (MV) with a median dose of 7 MV (IQR 5–18 MV). We further identified 17 patients who had CIED malfunction with RT. This group had a higher cumulative RT dose of 42.5 Gy (20–77 Gy) and a photon dose of 14 MV (12–18 MV). None of the malfunctions resulted in clinical symptoms. Using logistic regression, the predictors of CIED malfunction were photon beam energy use ≥10 MV (OR 5.73; 95% CI, 1.58–10.76), anatomical location of RT above the diaphragm (OR 5.2, 95% CI, 1.82–15.2), and having a CIED from the ICD group (OR 4.6, 95% CI, 0.75–10.2). Conclusion: Clinicians should be aware of predictors of CIED malfunction with RT to ensure the safety of patients.

Cardiac Implantable Electronic Device Dysfunctions in Patients Undergoing Radiotherapy A Prospective Cohort Study

BACKGROUND

Increasing numbers of patients with cardiac implantable electronic devices (CIEDs) are undergoing radiotherapy for cancer. The aim of the study was to prospectively evaluate the incidence, characteristics, and associated factors of CIED dysfunctions related to radiotherapy.

METHODS

Between April 2013 and March 2020, all patients with a CIED who underwent ≥1 radiotherapy session were enrolled. Patients were monitored according to a systematic protocol, including device interrogation before the 1^st and after each radiotherapy session. The primary endpoint was CIED dysfunction, defined as oversensing, total or partial deprogramming, and/or unrecoverable reset.

RESULTS

We included a total of 92 CIED radiotherapy courses: 77 (83.7%) in patients with a pacemaker and 15 (16.3%) in those with an implantable cardioverter defibrillator. Overall, 13 dysfunctions (14.1%) were observed during 92 courses (1509 sessions), giving an incidence of 0.9 per 100 sessions. These included nine deprogramming (three total resets to back-up pacing mode and six partial deprogramming that were all successfully reprogrammed), three transient oversensing, and one unrecoverable oversensing requiring CIED and leads replacement. There were no adverse clinical events related to device dysfunction. In multivariable analysis, neutron-producing irradiation (odds ratio [OR], 5.59; 95% confidence interval [CI], 1.09-28.65; P=0.039) and cumulative tumor dose (OR, 1.05; 95% CI, 1.01-1.10; P=0.007) remained significantly associated with CIED dysfunction.

CONCLUSIONS

In this prospective study, transient or permanent subclinical CIED dysfunction occurred in 14.1% of radiotherapy courses. Our findings emphasize the importance of high-energy beams and neutron-producing irradiation in risk assessment. This article is protected by copyright. All rights reserved.

Local dose rate effects in implantable cardioverter-defibrillators with flattening filter free and flattened photon radiation

Purpose

In the beam penumbra of stereotactic body radiotherapy volumes, dose rate effects in implantable cardioverter–defibrillators (ICDs) may be the predominant cause for failures in the absence of neutron-generating photon energies. We investigate such dose rate effects in ICDs and provide evidence for safe use of lung tumor stereotactic radioablation with flattening filter free (FFF) and flattened 6 Megavolt (MV) beams in ICD-bearing patients.

Methods

Sixty-two ICDs were subjected to scatter radiation in 1.0, 2.5, and 7.0 cm distance to 100 Gy within a 5 × 5 cm² radiation field. Radiation was applied with 6 MV FFF beams (constant dose rate of 1400 cGy/min) and flattened (FLAT) 6 MV beams (430 cGy/min). Local dose rates (LDR) at the position of all ICDs were measured. All ICDs were monitored continuously.

Results

With 6 MV FFF beams, ICD errors occurred at distances of 1.0 cm (LDR 46.8 cGy/min; maximum ICD dose 3.4 Gy) and 2.5 cm (LDR 15.6 cGy/min; 1.1 Gy). With 6 MV FLAT beams, ICD errors occurred only at 1 cm distance (LDR 16.8 cGy/min; 3.9 Gy). No errors occurred at an LDR below 7 cGy/min, translating to a safe distance of 2.5 cm (1.5 Gy) in flattened and 7 cm (0.4 Gy) in 6 MV FFF beams.

Conclusion

A LDR in ICDs larger than 7 cGy/min may cause ICD malfunction. At identical LDR, differences between 6 MV FFF and 6 MV FLAT beams do not yield different rates of malfunction. The dominant reason for ICD failures could be the LDR and not the total dose to the ICD. For most stereotactic treatments, it is recommended to generate a planning risk volume around the ICD in which LDR larger than 7 cGy/min are avoided.

In-vitro investigation of cardiac implantable electronic device malfunction during and after direct photon exposure: A three-centres experience

PURPOSE

Radiotherapy may cause malfunction of implantable cardioverter-defibrillators (ICDs) and pacemakers (PMs). We carried-out a multicentre randomized in-vitro study on 65 ICDs and 145 PMs to evaluate malfunctions during and after direct irradiation to doses up to 10 Gy.

METHODS

Three centres equipped with different linear accelerator and treatment-planning systems participated in the study. Computed Tomography (CT) acquisitions were performed to build the treatment plans. All devices were exposed to dose of 2, 5, or 10 Gy (6 MV). All devices underwent a baseline examination and 64 wireless real-time telemetry-transmissions (47 ICDs and 17 PMs) were monitored during photon exposures. All devices were interrogated after exposure and once monthly for six subsequent months.

RESULTS

Fifty-four of the 64 wireless-enabled CIEDs (84.4%) recorded noise-related interferences during exposure. In detail, 40/47 ICDs (85.1%) reported interference, of which 16 ICDs (34%) reported potentially clinically relevant pacing inhibition and inappropriate detections. Following exposure, a soft reset occurred in 1/145 PM (0.7%) while 7/145 PMs (4.8%) reported battery issues. During the six-month follow-up, 1/145 PM (0.7%) reported a soft reset, while 12/145 more PMs (8.3%) and 1/64 ICD (1.5%) showed abnormal battery depletion. All reported issues occurred independently of exposure dose. Finally, irreversible effects on software and battery life occurred in only non-MRI-compatible devices.

CONCLUSION

ICDs mostly featured real-time transient sensing issues, while PMs mostly experienced long-term battery or software issues that were observed immediately following radiation exposure and during follow-up. Irreversible effects on battery life and software occurred in only non-MRI-compatible devices.

Safety verification of carbon-ion radiotherapy for patients with cardiac implantable electronic devices (CIEDs)

According to guidelines, carbon-ion beam therapy is considered to carry a high safety risk for patients with cardiac implantable electronic devices (CIEDs), although the actual impacts remain unclear. In this study, we investigated the safety of carbon-ion beam therapy in patients with CIEDs. Patients with CIEDs who underwent carbon-ion therapy at Gunma University Heavy Ion Medical Center between June 2010 and December 2019 were identified and investigated for abnormalities in the operation of their CIEDs, such as oversensing and resetting during irradiation, and abnormalities in operation after treatment. In addition, the risk of irradiation from carbon-ion beam therapy was evaluated by model simulations. Twenty patients (22 sites) with CIEDs were identified, 19 with pacemakers and one with an implantable cardioverter-defibrillator (ICD). Treatments were completed without any problems, except for one case in which the treatment was discontinued because of worsening of the primary disease. Monte Carlo simulation indicated that the carbon beam irradiation produced neutrons at a constant and high level in the irradiation field. Nevertheless, with the distances between the CIEDs and the irradiation fields in the analyzed cases, the quantity of neutrons at the CIEDs was lower than that within the irradiation. Although carbon-ion beam therapy can be safely administered to patients with CIEDs, it is advisable to perform the therapy with sufficient preparation and backup devices because of the risks involved.

Assessment of Radiation-Induced Malfunction in Cardiac Implantable Electronic Devices

Background

Radiation therapy (RT) is a standard cancer treatment modality, and an increasing number of patients with cardiac implantable electronic devices (CIEDs) are being referred for RT. The goals of this study were as follows: (i) to determine the incidence of CIED malfunction following RT; (ii) to characterize the various types of malfunctions that occur; and (iii) to identify risk factors associated with CIED malfunction following RT.

Methods

A retrospective study of patients with CIEDs who received RT between 2007 and 2018 at 4 Canadian centres (Sunnybrook Health Sciences Centre, Kingston General Hospital, Hamilton Health Sciences Centre, and University of Ottawa Heart Institute) was conducted. Patients underwent CIED interrogation after completion of RT, to assess for late damage to the CIEDs. Data on demographics, devices, and RT were compared for the primary outcome of device malfunction.

Results

Of 1041 patients with CIEDs who received RT, 811 patients with complete data were included. Device malfunctions occurred in 32 of 811 patients (4%). The most common device malfunctions were reduced ventricular/atrial sensing (in 13 of 32 [41%]), an increase in lead threshold (in 9 of 32 [22%]), lead noise (in 5 of 32 [16%]), and electrical reset (in 2 of 32 [6%]). Higher beam energy (≥ 10 MV) was associated with malfunction (P < 0.0001). Radiation dose was not significantly different between the malfunction and non-malfunction groups (58.3 cGy vs 65 cGy, respectively, P = 0.71).

Conclusions

Although RT-induced CIED malfunctions are rare (occurring in 4% of patients with a CIED who undergo RT), collaborative efforts between radiation oncologists and cardiac rhythm device clinics to optimize CIED monitoring are needed, to detect and manage CIED malfunctions. Malfunctions are more common in patients receiving higher–beam energy (≥10MV)RT.

Current Clinical Practice in Patients With Cardiac Implantable Electronic Devices (CIED) Undergoing Radiotherapy (RT)

Patients with cardiac implantable electronic devices (CIED) undergoing radiotherapy (RT) are more common due to ageing of the population. With newer CIEDs implementing the complementary metal-oxide semiconductor (CMOS) technology which allows the miniaturisation of CIED, it is also more susceptible to RT. Effects of RT on CIED ranges from device interference, device operational/memory errors of permanent damage. These malfunctions can cause life threatening clinical effects. Cumulative dose is not the only component of RT that causes CIED malfunction, as neutron use and dose rate effect also affects CIEDs. The management of this patient cohort in clinical practice is inconsistent due to lack of a consistent guideline from manufacturers and physician specialty societies. Our review will focus on the current clinical practice and the recent updated guidelines of managing patients with CIED undergoing RT. We aim to simplify the evidence and provide a simple and easy to use guide based on the recent guidelines.

Study of feasible and safe condition for total body irradiation using cardiac implantable electronic devices

Cardiac implantable electronic devices (CIEDs) were believed to have a tolerance dose and that direct irradiation has to be avoided. Thus, no clinical guidelines have mentioned the feasibility of total body irradiation (TBI) with a CIED directly. The purpose of this work was to study a feasible and safe condition for TBI using a CIED. Eighteen CIEDs were directly irradiated by a 6-MV X-ray beam, where a non-neutron producible beam was employed for the removal of any neutron contribution to CIED malfunction. Irradiation up to 10 Gy in accumulated dose was conducted with a 100-cGy/min dose rate, followed by up to 20 Gy at 200 cGy/min. An irradiation test of whether inappropriate ventricular shock therapy was triggered or not was also performed by using a 6-MV beam of 5, 10, 20 and 40 cGy/min to two CIEDs. No malfunction was observed during irradiation up to 20 Gy at 100 and 200 cGy/min without activation of shock therapy. These results were compared with typical TBI, suggesting that a CIED in TBI will not encounter malfunction because the prescribed dose and the dose rate required for TBI are much safer than those used in this experiment. Several inappropriate shock therapies were, however, observed even at 10 cGy/min if activated. The present result suggested that TBI was feasible and safe if a non-neutron producible beam was employed at low dose-rate without activation of shock therapy, where it was not inconsistent with clinical and non-clinical data in the literature. The feasibility of TBI while using a CIED was discussed for the first time.

Current clinical practice in patients with cardiac implantable electronic devices undergoing radiotherapy: a literature review

Patients with cardiac implantable electronic devices (CIED) undergoing radiotherapy (RT) are more common due to the ageing of the population. With newer CIEDs' implementing the complementary metal-oxide semiconductor (CMOS) technology which allows the miniaturization of CIED, it is also more susceptible to RT. Effects of RT on CIED ranges from device interference, device operational/memory errors of permanent damage. These malfunctions can cause life-threatening clinical effects. Cumulative dose is not the only component of RT that causes CIED malfunction, as neutron use and dose rate effect also affects CIEDs. The management of this patient cohort in clinical practice is inconsistent due to the lack of a consistent guideline from manufacturers and physician specialty societies. Our review will focus on the current clinical practice and the recently updated guidelines of managing patients with CIED undergoing RT. We aim to simplify the evidence and provide a simple and easy to use guide based on the recent guidelines.

Focus on stereotactic radiotherapy: A new way to treat severe ventricular arrhythmias?

Ventricular tachycardia has a significant recurrence rate after ablation for several reasons, including inaccessible substrate. A non-invasive technique to ablate any defined areas of myocardium involved in arrhythmogenesis would be a potentially important therapeutic improvement if shown to be safe and effective. Early feasibility studies of single-fraction stereotactic body radiotherapy have demonstrated encouraging results, but rigorous evaluation and follow-up are required. In this document, the basic concepts of stereotactic body radiotherapy are summarized, before focusing on stereotactic arrhythmia radioablation. We describe the effect of radioablation on cardiac tissue and its interaction with intracardiac devices, depending on the dose. The different clinical studies on ventricular tachycardia radioablation are analysed, with a focus on target identification, which is the key feature of this approach. Our document ends with the indications and requirements for practicing this type of procedure in 2020. Finally, because of the limited number of patients treated so far, we encourage multicentre registries with long-term follow-up.

Safety of lung stereotactic ablative radiotherapy for the functioning of cardiac implantable electronic devices

BACKGROUND AND PURPOSE

The prevalence of patients with a cardiac implantable device (CIED) developing cancer and requiring a course of radiotherapy (RT) is increasing remarkably. Previously published reports agree that standard and conventionally fractionated RT is usually safe for CIEDs, but no "in-vivo" reports are available on the potential effects of thoracic stereotactic ablative radiotherapy (SABR) regimens to CIEDs functioning. The purpose of our study is therefore to evaluate the effects of SABR on CIEDs (pacemakers [PM] or implantable cardiac defibrillators [ICD]) in a cohort of patients affected by primary or metastatic lung lesions.

MATERIALS AND METHODS

We retrospectively collected all CIED-bearing patients undergoing SABR between 2007 and 2019 at our Institution. All CIEDs were interrogated before and after the SABR course to check for any malfunction. Prescription dose, beam energy and maximum dose (Dmax) to CIEDs were retrieved for each patient. Electrical records of the CIEDs were reviewed by the medical records.

RESULTS

Thirty-four consecutive patients (24 with a PM and 10 with an ICD), who underwent 38 separate SABR courses, were included in the study. Eight patients (24%) were PM-dependent. Prescription dose of SABR ranged 26-60 Gy in 1-8 fractions, with a photon energy ranging 6-to-10 MV (76.3% and 23.7%, respectively) and a median Dmax to CIEDs of 0.17 Gy (range 0.04-1.97 Gy). Electrical parameters were stable in post-treatment device programming visits and no transient or persistent alteration of the CIED function was recorded in any patient. No inappropriate interventions were recorded in the 10 ICD-bearing patients during the treatment fractions.

CONCLUSIONS

Thoracic SABR proved to be safe for CIEDs when the dose is kept <2 Gy and the beam energy is ≤10 MV, irrespective of the pacing-dependency and of the CIED type.

Joint Position Paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology (SFC) and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) on magnetic resonance imaging in patients with cardiac electronic implantable devices

Magnetic resonance imaging (MRI) has become the reference imaging for the management of a large number of diseases. The number of MR examinations increases every year, simultaneously with the number of patients receiving a cardiac electronic implantable device (CEID). A CEID was considered an absolute contraindication for MRI for years. The progressive replacement of conventional pacemakers and defibrillators by MR-conditional CEIDs and recent data on the safety of MRI in patients with "MR-nonconditional" CEIDs have progressively increased the demand for MRI in patients with a CEID. However, some risks are associated with MRI in CEID carriers, even with "MR-conditional" devices because these devices are not "MR-safe". A specific programing of the device in "MR-mode" and monitoring patients during MRI remain mandatory for all patients with a CEID. A standardized patient workflow based on an institutional protocol should be established in each institution performing such examinations. This joint position paper of the Working Group of Pacing and Electrophysiology of the French Society of Cardiology and the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV) describes the effect and risks associated with MRI in CEID carriers. We propose recommendations for patient workflow and monitoring and CEID programming in MR-conditional, "MR-conditional nonguaranteed" and MR-nonconditional devices.

Radiotherapy in Patients With a Cardiac Implantable Electronic Device

Recently, the Heart Rhythm Society published recommendations on management of patients with cardiac implantable electronic device (CIED) who require radiotherapy (RT). We aimed to report the experience of a teaching hospital, and discuss our practice in the context of recently published guidelines. We identified all consecutive CIED recipients (12,736 patients) who underwent RT between March 2006 and June 2017. Among them, 90 (1%) patients (78.2 ± 10 years, 73% male) had a CIED: 82 pacemakers and 8 implantable cardioverter-defibrillators. Two patients required CIED extraction prior to RT for ipsilateral breast cancer (no device replacement in 1 patient). Four patients (5%) were considered at high-risk, 35 (39%) at intermediate-risk, and the remaining 50 (56%) at low-risk for CIED dysfunction. Overall, only a minority of patients followed recommended local protocol during RT delivery (31%) and during follow-up (56%). CIED malfunction was detected in 5 patients (6%), mainly back-up mode resetting (80%), with 4 (including 3 pelvic cancer location) patients initially classified as being at intermediate-risk and 1 at low-risk. Four out of the 5 patients with CEID malfunction had received neutron producing beams. In conclusion, our findings underline the lack of rigorous monitoring of patients undergoing RT (though CIED malfunction appears to be rare and relatively benign in nature), and emphasize the interest of considering neutron producing beam for risk stratification as recommended in recent guidelines. Optimization of patient's management requires a close collaboration between both CIED clinicians and radiation oncologists, and more systematic remote CIED monitoring may be helpful.

A randomized in vitro evaluation of transient and permanent cardiac implantable electronic device malfunctions following direct exposure up to 10 Gy

BACKGROUND AND PURPOSE

High-dose 6‑MV radiotherapy may cause cardiac implantable electronic devices (CIEDs) to malfunction. To assess CIED malfunctions resulting from direct exposure up to 10 Gy, 100 pacemakers (PMs) and 40 implantable cardioverter-defibrillators (ICDs) were evaluated.

MATERIALS AND METHODS

CIEDs underwent baseline interrogation. In ICDs, antitachycardia therapies were disabled via the programmer while the detection windows were left enabled. A computed tomography (CT) scan was performed to build the corresponding treatment plan. CIEDs were "blinded" and randomized to receive single doses of either 2, 5, or, 10 Gy via a 6-MV linear accelerator (linac) in a water phantom. Twenty-two wireless telemetry-enabled CIEDs underwent a real-time session, and their function was recorded by the video camera in the bunker. The CIEDs were interrogated after exposure and once monthly for 6 months.

RESULTS

During exposure, regardless of dose, 90.9% of the CIEDs recorded electromagnetic interference, with 6 ICDs (27.3%) reporting pacing inhibition and inappropriate arrhythmia detections. After exposure, a backup reset was observed in 1 PM (0.7% overall, 1% among PMs), while 7 PMs (5% overall, 7% among PMs) reported battery issues (overall immediate malfunction rate was 5.7%). During follow-up, 4 PMs (2.9% overall; 4% among PMs) and 1 ICD (0.7% overall; 2.5% among ICDs) reported abnormal battery depletion, and 1 PM (0.7% overall; 1% among PMs) reported a backup reset (overall late malfunction rate was 4.3%).

CONCLUSION

Apart from transient electromagnetic interference, last-generation CIEDs withstood direct 6‑MV exposure up to 10 Gy. Permanent battery or software errors occurred immediately or later only in less recent CIEDs.

The effect of stereotactic body radiotherapy (SBRT) using flattening filter-free beams on cardiac implantable electronic devices (CIEDs) in clinical situations

PURPOSE

This study focused on determining risks from stereotactic radiotherapy using flattening filter-free (FFF) beams for patients with cardiac implantable electronic device (CIEDs). Two strategies were employed: a) a retrospective analysis of patients with CIEDs who underwent stereotactic radiosurgery (SRS)/SBRT at the Peter MacCallum Cancer Centre between 2014 and 2018 and b) an experimental study on the impact of FFF beams on CIEDs.

METHODS

A retrospective review was performed. Subsequently, a phantom study was performed using 30 fully functional explanted CIEDs from two different manufacturers. Irradiation was carried out in a slab phantom with 6-MV and 10-MV FFF beams. First, a repetition-rate test (RRT) with a range of beam pulse frequencies was conducted. Then, multifraction SBRT (48 Gy/4 Fx) and single-fraction SBRT (28 Gy/1 Fx) treatment plans were used for lung tumors delivered to the phantom.

RESULTS

Between 2014 and 2018, 13 cases were treated with an FFF beam (6 MV, 1400 MU/min or 10 MV, 2400 MU/min), and 15 cases were treated with a flattening filter (FF) beam (6 MV, 600 MU/min). All the devices were positioned outside the treatment field at a distance of more than 5 cm, except for one case, and no failures were reported due to SBRT/SRS. In the phantom rep-rate tests, inappropriate sensing occurred, starting at a rep-rate of 1200 MU/min. Cardiac implantable electronic device anomalies during and after delivering VMAT-SBRT with a 10-MV FFF beam were observed.

CONCLUSIONS

The study showed that caution should be paid to managing CIED patients when they undergo SBRT using FFF beams, as it is recommended by AAPM TG-203. Correspondingly, it was found that for FFF beams although there is small risk from dose-rate effects, delivering high dose of radiation with beam energy greater than 6 MV and high-dose rate to CIEDs positioned in close vicinity of the PTV may present issues.

Effects of high-energy photon beam radiation therapy on Jarvik 2000 LVAD: in vitro evaluation

PURPOSE

Left ventricular assist device (LVAD) is considered a standard care for patients with advanced heart failure. The aim of this work was to study in vitro the effects of direct exposure of the Jarvik 2000 LVAD to 10-MV photon beams.

METHODS

Jarvik 2000 pump was immersed in a siliconized box filled with deionized water. A 30 × 30 × 15 cm RW3 slabs were added forth and back to the box. A treatment plan consisting of a single direct 10 × 10 cm² field size beam was used to deliver 1000 MU at the center of the pump. During irradiation, the external Flow Maker controller and the lithium battery were positioned away from the beam. Pump parameter data (included voltage, current and frequency) were measured, recorded and analyzed for changes in pump function among baseline, pre-irradiation, during irradiation, post-irradiation and after 6 months. The whole session lasted 6 months. The Mann-Whitney U test was used to compare the repeated measurements. X-ray radiation attenuation was also studied.

RESULTS

The parameters investigated remained stable over the 6 months; that is, no pump stops, alarms, events, operational changes or abnormalities during the discharge rate of the connected power sources, were encountered, confirmed by the Mann-Whitney U test applied to all sessions (p > 0.1). The measured X-ray attenuation differed from the calculated one by TPS by 34%.

CONCLUSION

The Jarvik 2000 resulted stable under direct X-ray beam of 10-MV energy. Its strong attenuation, however, can affect dose deposition in the pump in TPS, and it must be taken into account.

Interaction between CIEDs and modern radiotherapy techniques: Flattening filter free-VMAT, dose-rate effects, scatter radiation, and neutron-generating energies

BACKGROUND AND PURPOSE

Providing evidence for radiotherapy (RT)-induced effects on cardiac implantable electric devices (CIEDs) with focus on flattening filter free-volumetric modulated arc therapy (FFF-VMAT) at 6 and 10 MV as well as 3D-conformal radiotherapy (3D-CRT) at 18 MV.

MATERIALS AND METHODS

68 CIEDs (64 implantable cardioverter-defibrillators (ICDs) and 4 cardiac pacemakers (PMs)) were located on the left chest position on a slab phantom and irradiated under telemetrical surveillance either directly, or distant to 3D-CRT or FFF-VMAT, dose-rate 2500 cGy/min, and target dose of 150 Gy. Devices were placed within, close by (2.5 cm and 5 cm), and distant (35 cm) to the radiation field. Scatter radiation (SR) and photon neutrons (PN) were recorded. CIEDs were investigated in following groups: 1a) 18 MV 3D-CRT - 4 ICDs/4 PMs out of radiation field, 1b) 18 MV open field - 4 ICDs/4 PMs within radiation field, 2) 6 MV FFF-VMAT, 15 ICDs in 35 cm distance to VMAT, 3) 10 MV-FFF VMAT, 15 ICDs in 35 cm distance to VMAT, 4) 6 MV FFF-VMAT, 15 ICDs in 2.5 cm distance to VMAT, 5) 10 MV FFF-VMAT, 15 ICDs in 2.5 cm distance to VMAT.

RESULTS

No incidents occurred at 6 MV FFF. 10 MV FFF-VMAT and 18 MV 3D-CRT resulted in data loss, reset, and erroneous sensing with inhibition of pacing (leading to inadequate defibrillation) in 8/34 ICDs and 2/4 PMs which were not located within radiation. Direct radiation triggered instantaneous defibrillation in 3/4 ICDs.

CONCLUSIONS

6 MV FFF-VMAT is safe even at high dose-rates of 2500 cGy/min, regardless whether CIEDs are located close (2.5 cm) or distant (35 cm) to the radiation beam. CIEDs should never be placed within radiation and energy should always be limited to 6 MV. At 6 MV, VMAT at high dose-rates can be used to treat tumors, which are located close to CIEDs.

Management of radiotherapy patients with implanted cardiac pacemakers and defibrillators: A Report of the AAPM TG-203†

Managing radiotherapy patients with implanted cardiac devices (implantable cardiac pacemakers and implantable cardioverter-defibrillators) has been a great practical and procedural challenge in radiation oncology practice. Since the publication of the AAPM TG-34 in 1994, large bodies of literature and case reports have been published about different kinds of radiation effects on modern technology implantable cardiac devices and patient management before, during, and after radiotherapy. This task group report provides the framework that analyzes the potential failure modes of these devices and lays out the methodology for patient management in a comprehensive and concise way, in every step of the entire radiotherapy process.

Radiotherapy for patients with cardiovascular implantable electronic devices: an 11-year experience

PURPOSE

As cardiovascular implantable electronic devices (CIEDs) are increasingly indicated in older patients, and the burden of cancer is rising with the aging population, the management of patients with CIEDs who require radiotherapy (RT) is a timely concern. The objective of the study was to evaluate the management of, and malfunctions in, patients with CIEDs undergoing RT.

METHODS

A retrospective study of patients with CIEDs receiving RT at Kingston Health Sciences Center from March 2007-April 2018 was conducted. Data on demographics, RT, devices, and management were compared for the primary outcome of device malfunction.

RESULTS

Of the 189 patients with CIEDs receiving a total of 297 courses of RT, 4 patients (2.1%) experienced device malfunctions. Higher beam energy was associated with a malfunction (p < 0.05). Patients with malfunctions received a lower dose of radiation per fraction (267 ± 93 cGy vs. 477 ± 282 cGy; p < 0.05) and were significantly younger (71.4 ± 2.2 years vs. 77.8 ± 9.8 years; p < 0.01) compared to patients without malfunctions.

CONCLUSION

RT-induced device malfunctions are rare, but given the potential complications, a better understanding of the potential predictors of malfunction and the development of evidence-based guidelines will help optimize patient safety.

Radiotherapy for Patients with Cardiovascular Implantable Electronic Devices: A Review

Because cardiovascular implantable electronic devices are increasingly indicated in older patients, and the burden of cancer is rising with the growth and aging of the world population, the management of patients with cardiac devices who require radiotherapy for cancer treatment is a timely concern. Device malfunctions might occur in as high as 3% of radiotherapy courses, posing a substantial issue in clinical practice. A nonsystematic comprehensive review was undertaken. We searched PubMed and the MEDLINE database for randomized controlled trials, meta-analyses, systematic reviews, observational studies, in vitro/in vivo studies, and case reports. Articles were selected by 2 independent reviewers, and emphasis was given to information of interest to a general medical readership. The pathophysiology and predictors of cardiovascular implantable electronic device malfunction due to radiotherapy are reviewed, recommendations for the management of patients with such devices undergoing radiotherapy are summarized, and the clinical significance and future directions of this field are discussed. Radiotherapy-induced device malfunctions are rare, but because of the potential complications, the development of evidence-based guidelines for the management of patients with cardiovascular implantable electronic devices undergoing radiotherapy is a timely concern.

Radiotherapy-Induced Cardiac Implantable Electronic Device Dysfunction in Patients With Cancer

Radiotherapy can affect the electronic components of a cardiac implantable electronic device (CIED) resulting in malfunction and/or damage. We sought to assess the incidence, predictors, and clinical impact of CIED dysfunction (CIED-D) after radiotherapy for cancer treatment. Clinical characteristics, cancer, different types of CIEDs, and radiation dose were evaluated. The investigation identified 230 patients, mean age 78 ± 8 years and 70% were men. A total of 199 patients had pacemakers (59% dual chamber), 21 (9%) cardioverter-defibrillators, and 10 (4%) resynchronizators or defibrillators. The left pectoral (n = 192, 83%) was the most common CIED location. Sixteen patients (7%) experienced 18 events of CIED-D after radiotherapy. Reset to backup pacing mode was the most common encountered dysfunction, and only 1 (6%) patient of those with CIED-D experienced symptoms of atrioventricular dyssynchrony. Those who had CIED-D tended to have a shorter device age at the time of radiotherapy compared to those who did not (2.5 ± 1.5 vs 3.8 ± 3.4 years, p = 0.09). The total dose prescribed to the tumor was significantly greater among those who had CIED-D (66 ± 30 vs 42 ± 23 Gy, p <0.0001). Multivariate logistic regression analysis identified the total dose prescribed to the tumor as the only independent predictor for CIED-D (odds ratio 1.19 for each increase in 5 Gy, 95% confidence interval 1.08 to 1.31, p = 0.0005). In conclusion, in this large population of patients with CIEDs undergoing radiotherapy for cancer treatment, the occurrence of newly diagnosed CIED-D was 7%, and the reset to backup pacing mode was the most common encountered dysfunction. The total dose prescribed to the tumor was a predictor of CIED-D. Importantly, although the unpredictability of CIEDs under radiotherapy is still an issue, none of our patients experienced significant symptoms, life-threatening arrhythmias, or conduction disorders.

Pacemaker malfunction associated with proton beam therapy: a report of two cases and review of literature-does field-to-generator distance matter?

It is well known that radiotherapy causes malfunctions of cardiac implantable electronic devices such as pacemaker (PM) and implantable cardioverter-defibrillator because of incidental neutron production. Here, we report our experience with two cases of PM reset among seven patients with PM who underwent proton beam therapy (PBT) from January 2011 to April 2015 at our centre. Our experience shows PM reset can occur also with abdominal PBT. In both cases, PM reset was not detected by electrocardiogram (ECG) monitoring but was rather discovered by post-treatment programmer analysis. Our cases suggest that PM malfunction may not always be detected by ECG monitoring and emphasize the importance of daily programmer analysis.

Clinical management of electromagnetic interferences in patients with pacemakers and implantable cardioverter-defibrillators: review of the literature and focus on magnetic resonance conditional devices

The number of cardiac implantable electronic devices (CIEDs) has greatly increased in the last 10 years. Many electronic devices used in daily activities generate electromagnetic interferences (EMIs) that can interact with CIEDs. In clinical practice, it is very important to know the potential sources of EMIs and their effect on CIEDs in order to understand how to manage or mitigate them. A very important source of EMI is magnetic resonance (MR), which is considered nowadays the diagnostic gold standard for different anatomical districts. In this review, we focused on the effects of EMI on CIEDs and on the clinical management. Moreover, we made a clarification about MR and CIEDs.In patients with CIEDs, EMIs may cause potentially serious and even life-threatening complications (inappropriate shocks, device malfunctions, inhibition of pacing in pacemaker-dependent patients) and may rarely dictate device replacement. The association of inappropriate shocks with increased mortality highlights the importance of minimizing the occurrence of EMI. Adequate advice and recommendations about the correct management of EMIs in patients with CIEDs are required to avoid all complications during hospitalization and in daily life. Furthermore, the article focused on actual management about MR and CIEDs.

Monitoring of CRT-D devices during radiation therapy in vitro

Background

Using of active cardiac medical devices increases steadily. In Europe, there were 183 implants of ICD and 944 implants of PM, 119 of biventricular ICD and 41 of biventricular PM, all per million inhabitants in 2014. Healthcare environments, including radiotherapy treatment rooms, are considered challenging for these implantable devices. Exposure to radiation may cause the device to experience premature elective replacement indicator, decreased pacing amplitude or pacing inhibition, inappropriate shocks or inhibition of tachyarrhythmia therapy and loss of device function. These impacts may be temporary or permanent. The aim of this study was to evaluate the influence of linear accelerator ionizing radiation dose of 10 Gy on the activity of the biventricular cardioverter-defibrillator in different position in radiation beam.

Methods

Two identical wireless communication devices with all three leads were used for the measurement. Both systems were soused into solution saline and exposed in different position in the beam of linear accelerator per 10 Gy fractions. In comparison of usually used maximum recommended dose of 2 Gy, the radiation doses used in test were five times higher. Using the simultaneous monitoring wireless communication between device and its programmer allowed watching of the devices activities, noise occurrence or drop of biventricular pacing on the programmer screen, observed by local television loop camera.

Results

At any device position in radiation beam, there were no influences of the device activity at dose of 10 Gy neither a significant increase of a solution saline temperature in any of the measured positions of CRT-D systems in linear accelerator.

Conclusions

The results of the study indicated, that the recommendation dose for treating the patients with implantable devices are too conservative and the risk of device failure is not so high. The systems can easily withstand the dose fractions of tens Gy, which would allow current single-dose-procedure treatment in radiation therapy. Even though the process of the random alteration of device memory and electrical components by scatter particles not allowed to specify a safe dose during ionizing radiation, this study showed that the safe limit are above the today used dose fractions.

Radiotherapy in patients with pacemakers and implantable cardioverter defibrillators: a literature review

An increasing number of patients with implantable cardiac rhythm devices undergo radiotherapy (RT) for cancer and are thereby exposed to the risk of device failure. Current safety recommendations seem to have limitations by not accounting for the risk of pacemakers and implantable cardioverter defibrillators malfunctioning at low radiation doses. Besides scant knowledge about optimal safety measures, only little is known about the exact prevalence of patients with devices undergoing RT. In this review, we provide a short overview of the principles of RT and present the current evidence on the predictors and mechanisms of device malfunctions during RT. We also summarize practical recommendations from recent publications and from the industry. Strongly associated with beam energy of photon RT, device malfunctions occur at ∼3% of RT courses, posing a substantial issue in clinical practice. Malfunctions described in the literature typically consist of transient software disturbances and only seldom manifest as a permanent damage of the device. Through close cooperation between cardiologists and oncologists, a tailored individualized approach might be necessary in this patient group in waiting time for updated international guidelines in the field.

A case of radiotherapy for an advanced bronchial carcinoma patient with implanted cardiac rhythm machines as well as heart assist device

We present a case of radiotherapy for a 66-year-old patient with squamous cell carcinoma on the left main bronchus undergoing implantation of pacemaker, implantable cardioverter defibrillator (ICD) as well as cardiopulmonary support (CPS) device. The radiation area was determined according to 4D List Mode positron emission tomography–computed tomography (PET-CT) data. Planning Target Volume (PTV) included a part of the active ICD. For the optimal tumor coverage and sparing of both the implantable cardiac devices and organs at risk, we combined the conformal radiotherapy with stereotactic body radiotherapy (SBRT) using helical tomotherapy. The prescription dose of 25.2Gy was applied by conventional radiotherapy. SBRT was performed hypofractionated with a prescription dose of 35Gy in 5 fractions. A dynamic electrocardiogram was performed during every radiation fraction. The implanted aggregates were checked three times a week. Despite partial localization of the active ICD in the radiation field, the tumor was treated without inappropriate shock delivery during radiation treatment and over twelve months afterwards. The reduced tumor size as well as tumor metabolic activity were observed by PET-CT three months after radiation treatment. The patient exhibited no signs of pneumonitis on the last radiological follow-up examination six months after radiotherapy. The reduced dyspnea and cough over the first four months after treatment were observed.

In conclusion, tumor shrinkage and temporary clinical improvement of the patient as well as no technical complications of implanted cardiac devices were achieved by the radiation treatment.

DEGRO/DGK guideline for radiotherapy in patients with cardiac implantable electronic devices

An increasing number of patients undergoing radiotherapy (RT) have cardiac implantable electronic devices [CIEDs, cardiac pacemakers (PMs) and implanted cardioverters/defibrillators (ICDs)]. Ionizing radiation can cause latent and permanent damage to CIEDs, which may result in loss of function in patients with asystole or ventricular fibrillation. Reviewing the current literature, the interdisciplinary German guideline (DEGRO/DGK) was developed reflecting patient risk according to type of CIED, cardiac condition, and estimated radiation dose to the CIED. Planning for RT should consider the CIED specifications as well as patient-related characteristics (pacing-dependent, previous ventricular tachycardia/fibrillation). Antitachyarrhythmia therapy should be suspended in patients with ICDs, who should be under electrocardiographic monitoring with an external defibrillator on stand-by. The beam energy should be limited to 6 (to 10) MV CIEDs should never be located in the beam, and the cumulative scatter radiation dose should be limited to 2 Gy. Personnel must be able to respond adequately in the case of a cardiac emergency and initiate basic life support, while an emergency team capable of advanced life support should be available within 5 min. CIEDs need to be interrogated 1, 3, and 6 months after the last RT due to the risk of latent damage.